I had always thought so. But there are features on the Galaxy's primary hull that don't show up on the Nebula's It also looks like the Nebula's saucer might be missing a few decks as well. And I thought I had read stats that suggested a ship width of 300-odd meters instead of the Galaxy's 460-odd meters. Additionally, have we seen any other pods for the Nebula than the triangular tactical pod and the oval AWACs-style pod?
Pretty much all your answers are here: http://www.ex-astris-scientia.org/articles/nebula.htm There are arguably more than the two pod designs seen on the Phoenix and then the Sutherland et.al. - Sisko may have served on a variant with two smaller warp nacelles instead of a pod, since he has a model of it on his desk on DS9. Can they still be called Nebula class despite having different shapes and sizes of saucer, secondary hull and pod? Probably... There are eight (soon to be 11!) principal variants of the Boeing 737 that fall into two general "looks" of the aircraft, not counting different lengths of the main hull. They're all 737s, though. OTOH, there are quite a few variants of the Arleigh Burke class destroyer (including those operated by other countries) and they all have different class names.. Mark
It may also well be that the "generic" Galaxy saucer is fully compatible with the Nebula, but is only installed in exceptional cases, because it's far from optimal for the application. Say, during the Dominion War, standardized mass production of Galaxy saucers might be necessary, but the Nebula class would have no use for their impulse engines for reason X. For this reason, even the mass-produced saucers would have their engines faired over, in the manner we see e.g. on USS Bonchune - unless they received truly generic saucers that would soon be transferred to Galaxies and for that reason would retain the dead weight of the impulse engines. A dedicated peacetime Nebula would have the completely different impulse engine arrangement familiar from the earlier physical models, such as Phoenix or Farragut. Transferring such a saucer to a Galaxy would be possible, but then the saucer could not perform detached operations, and would be reduced to mere emergency separations. Perhaps Starfleet in the Dominion War wanted the detached operations capabilities of the Galaxy class, even though we virtually never saw this in combat or demonstrating combat value? Hence the "standardization" on Bonchune style rather than Farragut style saucers for the Nebula class, too. It may or may not have given the class the detached operations capability, but it would have kept the dockyards in the business of providing such capability for the other half of the fleet. Timo Saloniemi